Method of and apparatus for road-making.



i. A. JOHNSTON. METHOD OF AND APPARATUS FOR ROAD MAKING.

Patented Oct. 9. 1917.

APPLHIAHON HLED IUNE l4. WIS).

JOHN A. JOHNSTON, 0F SPRINGFIELD, MASSA GHUSETTS.

METHOD OF AND APPARATUS FOR ROAD-MAKING.

Specification of Letters Patent.

Patented Oct. 9, 1917.

Application fled June M, 1915. Serial No. 88,888.

To all whom it may concern:

Be it known that I, JOHN A. JOHNSTON, a citizen of the United States,residing at Springfield, in the county of Hampden and State ofMassachusetts, have invented a new and useful Method of and Apparatusfor Road-Making, of which the following is a specification.

This invention relates to the making of roads of either the bitumen orcement concrete type.

The principal objects of the invention are to provide for thoroughly andexpeditiously mixing the aggregate and matrix material during the travelof a vehicle or train of vehicles over the road bed and almostsimultaneously applying the mixture to the road bed; and especially toprovide for mixing the li uid or semi-liquid matrix material with t eaggregate material during the degceilt of the, same into position on theroad Further objects and advantages of the invention will appearhereinafter.

Reference is to be had to the accompanyin drawings in which,

igure 1 is a side view of a road-makin ap aratus constructed inaccordance wit the invention;

Fig. 2 is a longitudinal central sectional view of a portion of thesame; and

Fig. 3 is a similar view showing a constructioh-suitable for depositingcement concrete.

There is a well-known type of road building in which sand is mixed withheated bitumen, usually with equal parts of sand and bitumen, and themixture is used for fillin the interstices in the reviously prepared bedof stone particles. his is open to some difiiculties by reason of thefact that the sand has a tendency to sink, and to so segreate as to makethe uniform ap lication of t e mixture a difiicult problem. hisdisadvantage is overcome by this invention, which can be used for makingnew roads or resurfacing. Furthermore, complaint is often made of theordinary road surfacin methods because the tar is laid and of en leftexposed for a period of time before it is covered, thus leaving a stickysurface.

7 mixture as described the mass can The apparatus is shown as comprisinga vehicle 10 provided with a tank 11 thereon for receivin andtransporting the liquid material. T is is shown as drawin a secondvehicle 12 which is provided witg a load of fine aggregate material,preferably in the form of sand or fine stones, but it may range in sizefrom an impalpable powder to stones or fra merits two or more mches indiameter. his vehicle is also provided with a moving bottom 13 forconstantly forcing the solid particles rearwardly and delivering themover a roller 14 to a distributing cylinder 15. The material then fallsin a sheet from the vehicle and is deposited on the road bed. A shield16 is provided to prevent scattering.

From the tank 11 there extends a pipe 17 rearwardly and this isconnected with a transverse spray pipe 18. Although one such pipe isenough in some cases, any number may be used and I have shown two in thepresent instance, both connected with the pipe 17 so as to receive asupply of fluid therefrom. One is located in front of, and the other atthe rear of, the descending sheet of fine aggregate material. These twosupply pipes are so located that the spray openings will eject a sprayof liquid therefrom toward the stream of fine particles and come intocontact with the se me on both sides before it reaches the road bed. Inthis way the matrix and aggregate material are thoroughly mixed, or inother words the particles of ag regate material are substantiallycovered y the matrix while they are in a separated condition. Thisaction, of course, takes. lace just before the aggregate material reaces the road bed so as to be deposited upon it. The surfaces are stillmolten and sticky and the force of the falling particles is so increasedby the liquid being forced against them, as to assist in compacting themixture on the road bed and causing it to fill and seal any intersticeswhich may be present.

Although in the above description I have referred to the aggregate andmatrix material as falling on the road bed, it will be understood thatif fine sand is used, an 31c posited on a previously prepared bed ofcoarser aggregate material, as for example, broken stone. However, inthe present case, I have shown a third vehicle 20 trailing behind thevehicle 12 and provided with a movable bottom and distributing mechanismsimilar to that shown on the vehicle 12 for distributing a coarseaggregate material on the surface produced by the mixture of sand andbitumen or cement. It will be understood that this coarse a gregatematerial is then immediately rolled into the soft surface on which it isdeposited. This constitutes an expeditious and practical method ofproducin a roadway of this character.

t will be understood, however, that the invention is not limited to theuse of any particular matrix material or any particular aggregatematerial or materials, as it can be applied in the manufacture of cementroads in which case the previously mixed cement in a thin creamycondition may be used as a matrix material, or the cement may be mixedin a dry state with the aggregate material and the combination wet withthe sprays. The latter is shown in Fig. 3. In this case the dry cement,usually mixed with sand or gravel, is fed down the chute 21 so as tofall over the alternately slanting guides 22 and water is sprayed on itduring its descent from pipes 23.

The coarse aggregate material can be distributed by the vehicle 12 andcoated with the matrix material in the manner shown in Fig. 2 inconnection with that vehicle without the use of the third vehicle and infact some of my claims are not limited to any number of vehicles.

Although I have illustrated and described only one form of ap aratus anda certain procedure and by w 'ch the method can e carried out, I amaware of the fact that many modifications can be made in both withoutdeparting from the scope of the invention as expressed in the claims.

Therefore, I do not wish to be limited in these respects, but what I doclaim is 1. A method of road building which consists in discharging athin sheet of particles of aggregate material on the road and during itsprogress toward the road-bed and while falling freely in the airdischarging liquid or semi-liquid matrix material in thin sheets on bothsides of the sheet of aggregate material, whereby the individualparticles of aggregate material will be covered with the matrix materialduring their travel toward the road-bed and before the particles ofaggregate material are compacted together and the aggregate materialwill be deposited on the road-bed in a, freshly covered condition, thematrix material being directed in sprays against the falling agnectedwith sai receptacle for discharging the aggregate material and dro pingit on the road-way in a thin sheet, an means connected with said tankfor spraying the matrix material therefrom on the two opposite surfawsof said sheet of aggregate as it drops toward the road bed.

3. The combination of a. vehicle having a receptacle thereon forcontaining a body of matrix material adapted to harden upon continuedexposure, a second vehicle with the same adapted to support a body ofaggregate material, mechanical means on the second vehicle forpositively discharging the aggregate material, separating it in the airand dropping it in a continuous stream on the roadway, and meansextending from the matrix receptacle for delivering a spray of thematrix material on the bod of the aggregate material while in the air.

4. The combination of a vehicle having a tank thereon, a trailer behindthe same, means on the trailer for discharging a thin sheet of aggregatematerial downwardly, a

pipe extending from the tank and supported by the trailer, and twotransverse spray pipes connected with said pipe and located I onopposite sides of said, sheet.

5. In an apparatus for road building and the like, the combination of avehicle, and means supported thereby for producing two sprays of liquidmaterial under pressure with mechanical means whereby particles 0 solidmaterial are carried in a constant and uniform manner and delivered in'a thin sheet so as to fall between the lines of sprays produced bv thefirst-named means to insure a liquid coat on both sides of the sheet ofsolid partic es, the pressure of the sprays being so directed as to mistgravity in forcing the mixture into the road surface.

6. The combination of two vehicles, one

trailing behind the other, means carried by said vehicles for carryingand discharging matrix and aggregate materials, and means whereby thematrix and gate materials are directed toward the road way at pointsbetween the vehicles, the matrix material all being deposited inadvance, and aggre;

gate material being deposited upon it,

whereby the wheels of the vehicles will not have to pass over anuncoated matrix layer.

7 The combination with means for dischar ing matrix material on a roadbed, of a ve icle adapted to carry aggregate material, and means fordischarging the aggreposition to receive a regular and uniform gatematerial immediately after the matrix deposit of aggregate materialtherefrom by material is discharged, said means comprisgravity. 10 ingmeans for conveyin the aggregate ma- In testimony whereof I havehereunto set 5 terial along said vehic e, and a positively my hand.

driven distributing device located at the discharge end of saidconveying means in JOHN A. JOHNSTON.

